Electric glow discharge tube



Filed April 14, 1931 Ill INVENTOR Hi2?! mm BY ATTORNEY Patented 30, 1933 UNITEDSTATES PATENT OFFICE,

HEBBE BIHIA, OF EINDHOVEN, NETHERLANDS, ASSIGNOR N RADIO CORPORATION -OF AMERICA, A. OORIPOBATION.OF DELAWARE 7 ELEUDRIC GLOW DISCHARGE TUBE Application filed April 14, 1931, Serial No. 529,909, and in. the Netlzu'erlamlr April 15, 1980.

This invention relates to an electric glow discharge tube adapted for translating electrical. current variations into light variations. Glow discharge tubes of this type are i frequentl used in apparatus for receivmg images w ich are transmitted by telegraphy or by wireless, for example, in television apparatus.

When using low discharge tubesof this type often the difficulty is encountered, that ey shine afterward,-i. e., on variations of a the current traversing a discharge tube the intensity of the emitted light cone does not directly vary to the same extent as the ourrent.- On' weakenin of the current the luminous intensity still conserves its former value for a short time.

The present invention has for its purpose to obviate this afterglow.

In a glow dischargetube accordin invention the cathode formspart of t e wall of the discharge tube. The afterglow seems to be favourably affected by a good cooling of this cathode. Since the cathode forms part of the wall of the discharge tube it is rendered possible to coolthe cathode artificially in a simple manner; To this effect preferably the outer wall of the cathode is provided with a cavity through which a coolmg li uid may be passed. If the cavity is provi ed with a screw thread then a tube serving for the su ply of the coolingliquid, which (preferably y means of a artition is divide 7 into two passages, may screwed therein.

Due to the intensive cooling of the cathodetheafterglow is reduced and in addition a strong current may; be lead through the dischar tube, so that the intensity of the emi light may be raised. v

Theinventio'n will be more clearly understood by reference to the accompanying drawin representing, by way of example, one em 'ment thereof.

.The discharge tube illustrated comprises a wall 1 consisting of glass or similar material to which a metal body 2 consisting, for

ei'ample, of ferrochromium is sealed. The

outer wall of this body 2 comprises a cavity 9 '3, which is provided with a screw thread by means of which the tube 4 may be fixed to the metal body 2. By means of a partition with a deep and narrow recess 6 and is sur.- rounded by a cap. 7 of insulating material,

for examp quartz. This insulating envelope is surrounded in its turn by an electrically conducting cap .8 likewise consisting, for example, of ferrochromium and connected to the leading-in wire 9 which is taken out through the wall of the discharge tube.

The current may be supplied to the cathode through the metal tube 4. The envelope 7 and t e cap em provided with bores 10 and 11 re 'stering with the excavation 6 of the oath e.

The discharge tube is provided .with a gaseous filling preferably consisting of one or more rare gases, for example helium at a pressure of 15 millimetres. One or more metal vapours maybe added to the gaseous filling, which is often advisable in order to act upon'the spectrum of the light emitted by the discharge tube. If the tube contains mercury vapour, for example, then ultraviolet rays will be enerated by the discharge. If the wall of t e discharge tube consists of a material which is transparent to ultraviolet. rays, for example,- uviol glass or quartz these rays will emerge from the wall of thedischar tube.

on applying a suitable tension betweenthe cathode 2 and the anode 8 a negative glow discharge is produced between these electrodes. The luminous phenomena will be substantially concentrated in the recess 6 of] the cathode. It has been found that the va-' riations of the current passed through the tube is very quickly followed by the luminous intensity, so that, the afterglow of the discharge which may be very annoying when using the discharge tube, is obviated. More over, since the'heat produced by the disgiven a comparatively high value, due to which the intensity of the emitted light cone is raised.

Having now described In invention what- I claim and desire to secure y Letters i'atent is the following: o

A glow discharge device comprising a gas filled envelope, a. cathode member having at one end a cavity extending internall thereof, tubular members secured within t e cavity through which cooling liquids are supplied to and carried away from the cathode sa1d cathode also having at its opposite end a tubular recess extending internally thereof for a substantial ortion of its longitudinal length, a layer 0 insulating material surroundin the outer portion of said cathode for S11 stantially the entire longitudinal length thereof and also having an aperture coinciding in location with the said tubular cathode recess, and an anode member provided as a cap portion surrounding said insulation layer and having a recess coinciding in location with both the cathode tubular recess and the insulation layer aperture whereby upon the application of a potential difference between the anode and cathode members a low discharge is produced which is observe 1e in the direction of the longitudinal recess in the said cathode member.

\ HEBRE RINIA. 

